PRGM mode doesn't work on HP-25



#7

Hello all,

I have this HP-25 that is in very good cosmetic condition and as all the keys working, but there are some strange problems with it.

1 - The STO and RCL keys work, but I cannot recall what I've saves in the registers, I always get an 0
2 - In PRGM mode, I can write my program, and it shows the steps like it should, but when I try to RUN it ... nothing, I always get an 0

Can anybody help me fixing it?

Regards,
Jorge


#8

Hi Jorge,
I'm assuming you realize that the HP25 is volatile, and if turned off, all registers and program memory are lost.

Otherwise, it sounds like a power continuity problem causing data to be lost, most likely the battery contacts...which need to be scrupulously clean in a woodstock. Also be sure the all contact points within the battery pack are clean also. And be sure not to connect the calculator to the AC adapter unless you're positive you have a good battery pack with good contact installed (this could over-voltage the machine). I personally never connect my machine to an AC adapter, period. With my 29C I sometimes have to "seat" the battery pack by pressing it in the direction as if to remove it, but stopping short of actually removing it.
Best Regards, Hal


#9

Hello,

Thank you for your answer.

I've tried to clean the contacts and even that way (with the calculator plugged to the AC charger or not). the problems remain.

#10

Enter a few program keystrokes. If, upon review the operations change back to 13 00, the RAM IC has failed. Unfortunately, the only replacement source is from another 25.


#11

Hello,

yeah, it always keeps showing the 13 00 in program mode no matter whatever I write.
So this must be it's problem :(
Can I find the replacement part you told about in any other unit? For instance a cheaper HP-21 ?


#12

Unfortunately the HP-25 is generally the least expensive calculator that has the appropriate RAM chip. I have just posted to the articles forum a
comparison of Woodstock RAM chips.


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